Catalytic assembly



Sept. 20, 1955 w. M. BOWEN m CATALYTIC ASSEMBLY Filed Sept. 10, 1952 LLLF l M ANA Z IOu FIG.2.

INVENTOR. WILLIAM M. BOWEN,1]I

BY fla 2,,

I ATTORNEY FIG.4.

2,718,460 CATALYTIC ASSEMBLY William Bowen 111, Chester, Pa., assignor to Oxy- Catalyst, Inc, a corporation'of Pennsylvania Application September 10, 1952, Serial No. 308,838

8 Claims, 11. 23-288 This invention is concerned with a multi-unit catalytic assembly which is adapted to provide an extended area of catalytically active surface distributed throughout a predetermined volume of reaction space. The invention is particularly concerned with an assembly in which substantially all the component parts are composed of high quality porcelain .or othersir nilar ceramic material.

In copending application Serial Number 159,191, .filed May 1, 1950, for Process and Apparatusfor Contacting Operations by Eugene J. l-Ioudry, a catalytic unit is described consisting of a .pair'o'f spaced-apart end plates with a plurality of elongated'elements extending between and supported by the end plates. The elongated elements are coated with, or composed of, catalytically active material'so as to provide a plurality of catalytically active surfaces disposed in spaced-apart relationship. These units are preferably composed of high quality porcelain provided with a relatively thinflfilm of catalytically active material. ,They are particularly designed for carrying out reactions'at relatively high temperatures involving relatively high gas flow 'through the catalyst such as in the catalytic oxidation of organic vapors diluted in large volumes of air. Particularly when composed of porcelain or other ceramic material, these units are necessarily rather small. A commercial unit, for example, may have end plates three inches square supporting between them rod-like elements about six inches long. Consequently, in order to proyide a relatively large area of catalytically active surface, a number of units must be employed in conjunction with one another, The present invention is concerned with a catalytic assembly made up of a plurality of these units arranged inan advantageous manner such that the proper flow conditions of reactants through the assembly will be maintained, such that the assembly can be installed and dismantled quickly and without damage to the units, such that each catalytic surface is supported out of contact with "other parts of the assembly, and such that wide variations in temperature occurring during use will not damage the assembly as a whole, nor any of the individual units.

Reference is'now made to the accompanying drawings in which Fig. '1 is a perspective view of a catalytic assembly constructed in accordance with the invention; and,

Fig. 2 is an enlarged cross-sectional view of one of the units making up the assembly shown in Fig. l; and, i

Fig. 3 is an enlarged cross-sectional view of an elongated element making up the unit illustrated in Fig. 2; and,

Fig. 4 is a plan view of several unitsarranged in sideby-side relationship.

Referring first to Fig. 2 showing a cross-sectional view of one of the units-making up the assembly, the reference numeral '10 refers to spaced-apart end plates. End plates are provided with apertures 11 for receiving a plurality of elongated rod-like elements 12 in such manner that these elements extend between, and are supported by, the end plates; The rod-like elements '12 are disposed in a plurality of rows, with elements in alternate rows staggered with respect to those in intervening rows.

Ice 2,718,460

Patented Sept. 20, 1955 2 This explains why, in the cross-sectional view shown in Fig. 2, alternate elements are shown in section while those intervening are shown in plan. To permit longitudinal expansion of elements 12 when exposed to high temperature, at least one end of each element should be left free, suitable end play in the recesses 11 being provided .to permit this expansion. A central supporting post 13 is rigidly secured in sockets 13a provided in end plates 10 so as to maintain the end plates in fixed relationship to one another. As can be seen,

the marginal portions 10a of the end plates 10 project somewhat beyond the outermost rows of element 12. These projecting margins permit the unit to be supported by means of end plates 10 with the elements 12, providing the catalytically active surface, entirely out of contact with the supporting structure.

In order to minimize the pressure drop as fluids flow through the unit illustrated in Fig. 2, the elongated rod-like elements 12 are preferably provided with a streamlined contour as illustrated in Fig. 3 of the drawings. As shown in Fig. 3, the element is of tear drop shape in cross-section, the leading edge 14 being rounded, and the element tapering in width toward the trailing edge 15. Direction of flow of fluid with respect to the element is indicated by the arrow .16.

Reference is now made .to Fig. 1..of the drawings which shows an assembly of catalytic units arranged-within'a casing of firebrick 17. In one typical application of the assembly, for example, the enclosure of firebrick illustrated may comprise a section of a chimney fluecations, the entire assembly may be supported within the chimney flue, or in any other desiredlocation, by means of an iron grating 18 which is itself supported by means not shown. The catalytic units are then stacked upon the grating or other suitable support in parallel horizontal rows, such as rows 19, .20, 21 and 22, and in .a pluralityof superimposed layers such as layers 23,, 24 and '25. As can be seen, the units are disposed in such .a fashion that the elongated elements 1.2 lie in a substantially horizontal pesition, and such that adjacent side-by-side units, such as units 26 and 27 have their. end plates in abutting relationship. The parallel horizontal rows in each layer are arranged immediately adjacent to one another so that the end plates of units in neighboring rows are disposed in back-to-back abutting relationship as shown. With this type of arrangement, the end plates are disposed in parallel horizontal rows, these horizontal rows of end plates being superimposed upon. one another in building up the various layers. Double rows of end plate are formed in the interior of the assembly by virtue .of the back-to-back relationship of end plates in adjoining rows.

As pointed out previously, the end plates of each unit are provided, with projecting marginal portions 10a which project somewhat beyond the outermost rows .of elongated elements 12. Because of the projecting margins 10a, when the units are stacked inside-by-side relationship in the assembly, vertical channels 28v are formed between each adjacent side-by-s'ideunit as .best seen in Fig. 4. To prevent fluid flowing through the assembly from preferent'ially passing through channels 28 and thus try-passing the catalytic surface provided by the elongated elements 12, units in alternate layers are staggered with respect to units in intervening layers in such manner that the units in each successive layer are approximately centered over a end plates as can be seen in Fig. 1,, it can be seen that the end plates in successive layers are staggered with respect to one another in much the same manner as bricks or building blocks are staggered in a masonry wall. This arrangement forces fluid flowing through the assembly in the direction indicated by the arrows 29 to flow through each individual unit over and between the elongated elements 12 providing the catalytically active surface, and thereby obviates by-passing through the channels 28.

To give the assembly stability and to insure against displacement of any of the units with the consequent danger of breakage of the relatively fragile elongated elements 12, each of the superimposed layers are spaced and separated from one another by horizontal beams 30 disposed between, and longitudinally of superimposed rows of end plates. Beams 30 are provided with upper and lower longitudinal channels 31 and 32 respectively for receiving themargins of end plates in the layers above and beneath the beam. As shown, the beams 30 may take the general configuration of an I-bearn. However, any other desired shape may be employed.

The depth of the channels 31 and 32 should be such that there is no contact between the rod-like elements 12 and the beams 30 so that each unit is supported on the beam entirely by means of its end plates. In this way, the relatively fragile elements 12 carry no burden but their own weight.

As can be seen, double rows of back-to-back end plates formed by adjoining rows of units are carried by beams having channels adapted to receive two end plates in back-to-back relation, whereby neighboring rows of units are retained against endwise separation from one another. Single rows of end plates at the ends of the assembly are preferably provided with beams having a channel width adapted to receive a single end plate as illustrated. The beams 30 are preferably constructed of a ceramic material'such as high quality porcelain, and in such case it will usually be desirable to provide beams of a relatively short length as illustrated in order to insure against breakage. Preferably, the beams 30 are of such a length relative to the size of the individual catalytic units that a joint between two units will not occur over a joint between two beam sections.

The use of the channeled beams in the manner illustrated permits the units to be stacked upon one another in a compact, stable assembly. The assembly may be installed and dismantled rapidly and easily since all the component parts are merely layed in position and retained in place by gravity. The channelled beams 30 not only support units in respective layers and tie neighboring rows of units together, but likewise completely eliminate the possibility of fluids channelling between rows of back-toback end plates.

The assembly provided by this invention is particularly advantageous when the component parts are all composed of a ceramic material such as of high quality porcelain. When exposed to widely varying temperatures, units of ceramic material cannot be subjected to constraint without the risk of breakage during expansion and contraction. In accordance with the invention, this danger is obviated since each unit is mounted in the assembly substantially independently of the others and consequently can expand and contract in a substantially independent manner. Suflicient tolerances are provided in the width of the channels provided bybeams 30 so that the end plates are not rigidly held in the channels, but rest therein with suflicient play to permit substantially independent expansion and contraction of each unit.

The catalytic assembly provided by the present invention may be employed for a variety of catalytic reactions, particularly those taking place in the gaseous phase at a relatively high temperature. As previously mentioned, one particularly advantageous application of the invention is in catalyticoxidation reactionssuch as, for example, the catalytic oxidation of solvent fumes from enamelling ovens, theoxidation of S02 to S03 and similar reactions. For this type of reactions, the elongated elements 12 are p v 4 preferably composed of a high quality porcelain and are provided with a thin, tightly adherent coat of the oxidation catalyst. A highly active and durable oxidation catalyst may be prepared by providing a relatively thin coating of alumina upon the porcelain elements 12 by the method described in U. S. Patent 2,580,806. After receiving the alumina coating the units are then dipped into a metal salt solution, preferably an aqueous solution of a platinum, palladium, silver or copper salt, after which the units are carefully dried and then subjected to a temperature high enough to decompose the metal salt. When the units are provided with a film of catalytically active material in this manner and supported in the assembly as illustrated and described, there is absolutely no danger of breakage of the relatively fragile porcelain elements 12, and no danger of the catalytic coating rubbing off by contact with other units. It is, of course, clear that the assembly is suitable for other-types of reactions than those specifically mentioned.

If desired, the number and spacing of the rod-like elements 12 may be varied so that the concentration of catalytic surface per unit volume of reaction space in difierent parts of the assemblycan be varied to suit the particular requirements of the reaction. For example, in carrying out an oxidation reaction it may be desired to control the intensity of the reaction so as to prevent too large a temperature increase in that part of the assembly first contacted by the stream of reactants. In such a case, the units in the first layer of the assembly to be contacted could be provided with a smaller number of elongated elements 12 spaced a greater distance apart as compared to the number and spacing of elongated elements in the units making up the succeeding layers. If, on the other hand, it were desired to progressively decrease the intensity of reaction, units in the top layers of the assembly could be provided with fewer elongated elements spaced at greater distances.

Instead of, or in addition to, controlling the reaction intensity by varying the concentration of catalytic surface area as described above, the intensity of the reaction may also be controlled by varying the type of catalytic surface in various parts of the assembly. In an oxidation reaction, for example, units in one part of the assembly could be provided with a very active catalyst such as a platinum containing catalyst, while in another part of the assembly a less active catalyst, such as a silver containing catalyst, could be employed.

I claim:

1. A multi-unit catalytic assembly adapted to provide an extended area of catalytically active surface distributed throughout apredetermined volume, each unit of said assembly comprising a pair of end plates and a plurality of rows of elongated elements providing catalytically active surfaces extending between and supported by said end plates, the end plates of each unit having marginal portions projecting somewhat beyond the outermost rows of elements supported thereby, said units being stacked in side-by-side relationship in a plurality of superimposed layers with said elongated elements in the horizontal position, and with the end plates of each side-by-side unit in abutting relationship, whereby a vertical channel is formed between each pair of adjacent side-by-side units by virtue of the projecting marginal portions of said end plates, the

units in alternate layers being staggered with respect to the units in intervening layers whereby channelling of fluid through the vertical channels between said units as fluid flows through the assembly is obviated. I

2. A multi-unit catalytic assembly adapted to provide an extended area of catalytically active surface distributed throughout a predetermined volume, each unit of said assembly comprising a pair of end plates and a plurality of elongated elements providing catalytically active surfaces extending between, and supported by, said end plates,

said units being stacked in side-by-side relationship in P tent-1. horizontal rows and in a plurality of superimposed layers in such manner that horizontal rows of end plates are superimposed upon one another, said superimposed layers being supported upon and spaced from one another by horizontal beams disposed between said superimposed rows of end plates and provided with upper and lower longitudinal channels for receiving the margins of end plates in layers immediately above and beneath said beams so as to thereby retain said units against displacement in the assembly.

3. A multi-unit catalytic assembly adapted to provide an extended area of catalytically active surface distributed throughout a predetermined volume, each unit of said assembly comprising a pair of end plates and a plurality of elongated elements providing catalytically active surfaces extending between, and supported by, said end plates, said units being stacked in side-by-side relationship in parallel horizontal rows and in a plurality of superimposed layers in such manner that horizontal rows of end plates are superimposed upon one another, and such that end plates in neighboring rows of units are disposed in back-to-back abutting relationship thus forming double rows of end plates in the interior of the assembly, said superimposed layers being supported upon and spaced from one another by horizontal beams disposed between, and longitudinally of, said superimposed rows of end plates, and being provided with upper and lower longitudinal channels for receiving the margins of end plates in layers immediately above and beneath said beams, beams disposed between rows of back-to-back end plates having upper and lower channels of the proper width to accommodate two back-to-back end plates in snug relationship whereby neighboring rows of units in the assembly are retained against endwise separation, and whereby channeling of fluids between said neighboring rows of units is obviated.

4. A multi-unit catalytic assembly adapted to provide an extended area of catalytically active surface distributed throughout a predetermined volume, each unit of said assembly comprising a pair of rectangular end plates and a plurality of rows of elongated elements providing catalytically active surfaces extending between and supported by said end plates, the end plates of each unit having marginal portions projecting somewhat beyond the outermost rows of elements supported thereby, said units being stacked in side-by-side relationship in horizontal rows and in a plurality of superimposed layers, said superimposed layers being supported upon and spaced from one another by horizontal beams disposed between said layers and provided with longitudinal channels for receiving the projecting margins of said end plates so as to retain said units against displacement in the assembly.

5. A multi-unit catalytic assembly adapted to provide an extended area of catalytically active surface distributed throughout a predetermined volume, each unit of said assembly comprising a pair of end plates and a plurality of elongated elements providing catalytically active surfaces extending between, and supported by, said end plates, said units being stacked in side-by-side relationship in horizontal rows and in a plurality of superimposed layers, the units in alternate layers being staggered with respect to the units in intervening layers whereby channeling of fluid between said units as said fluid flows through the assembly is obviated, said superimposed layers being supported upon and spaced from one another by horizontal beams disposed between said layers and provided with longitudinal channels for receiving the margins of said end plates so as to retain said units against displacement in the assembly.

6. A multi-unit catalytic assembly adapted to provide an extended area of catalytically active surface distributed throughout a predetermined volume, each unit of said assembly comprising a pair of rectangular end plates and a plurality of rows of elongated elements providing catalytically active surfaces extending between and supported by said end plates, the end plates of each unit having marginal portions projecting somewhat beyond the outermost rows of elements supported thereby, said units being stacked in side-by-side relationship in horizontal rows and in a plurality of superimposed layers with said elongated elements in the horizontal position, said units being stacked in such manner that horizontal rows of end plates are superimposed upon one another, and such that end plates in neighboring rows of units are disposed in backto-back abutting relationship thus forming double rows of end plates in the interior of the assembly, the end plates of each side-by-side unit being arranged in abutting relationship whereby a vertical channel is formed between each pair of adjacent side-by-side units by virtue of the projecting marginal portions of said end plates, the units in alternate layers being staggered with respect to the units in intervening layers whereby channeling of fluid through the vertical channels between said units as fluid flows through the assembly is obviated, said superimposed layers of units being supported upon and spaced from one another by horizontal beams disposed between superimposed rows of end plates and provided with upper and lower longitudinal channels for receiving the projecting marginal portions of end plates in layers immediately above and beneath said beams so as to thereby retain said units aganist displacement in the assembly, beams disposed between rows of back-to-back end plates having upper and lower channels of the proper width to accommodate two back-to-back end plates in snug relationship whereby neighboring rows of units in the assembly are retained against endwise separation, and whereby channeling of fluids between said neighboring rows of units is obviated.

7. An assembly in accordance with claim 6 in which said units are composed of ceramic material.

8. An assembly in accordance with claim 6 in which said units are composed of ceramic material and said elongated elements are provided with a film of catalytically active material.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A MULTI-UNIT CATALYTIC ASSEMBLY ADAPTED TO PROVIDE AN EXTENDED AREA OF CATALYTICALLY ACTIVE SURFACE DISTRIBUTED THROUGHOUT A PREDETERMINED VOLUME, EACH UNIT OF SAID ASSEMBLY COMPRISING A PAIR OF END PLATES AND A PLURALITY OF ROWS OF ELONGATED ELEMENTS PROVIDING CATALYTICALLY ACTIVE SURFACES EXTENDING BETWEEN AND SUPPORTED BY SAID END PLATES, THE END PLATES OF EACH UNIT HAVING MARGINAL PORTIONS PROJECTING SOMEWHAT BEYOND THE OUTMOST ROWS OF ELEMENTS SUPPORTED THEREBY, SAID UNITS BEING STACKED IN SIDE-BY-SIDE RELATIONSHIP IN A PLURALITY OF SUPERIMPOSED LAYERS WITH SAID ELONGATED ELEMENTS IN THE HORIZONTAL POSITION, AND WITH THE END PLATES OF EACH SIDE-BY-SIDE UNIT IN ABUTTING RELATIONSHIP, WHEREBY A VERTICAL CHANNEL IS FORMED BETWEEN EACH PAIR OF ADJACENT SIDE-BY-SIDE UNITS BY VIRTUE OF THE PROJECTING MARGINAL PORTIONS OF SAID END PLATES, THE UNITS IN ALTERNATE LAYERS BEING STAGGERED WITH RESPECT TO THE UNITS IN INTERVENING LAYERS WHEREBY CHANNELLING OF FLUID THROUGH THE VERTICAL CHANNELS BETWEEN SAID UNITS AS FLUID FLOWS THROUGH THE ASSEMBLY IS OBVIATED. 